60 patients who meet all inclusion criteria and none of the exclusion criteria will be treated with the BYM338 High Dose administered via intravenous infusion from Day 1 to Week 52, and up to Week 104.

Drug: BYM338/bimagrumab

BYM338 will be administered via intravenous infusion to randomized patients beginning on Day 1 through Week 52, and up to Week 104.

Experimental: BYM338/bimagrumab Mid Dose

60 patients who meet all inclusion criteria and none of the exclusion criteria will be treated with the BYM338 Mid Dose administered via intravenous infusion from Day 1 to Week 52, and up to Week 104.

Drug: BYM338/bimagrumab

BYM338 will be administered via intravenous infusion to randomized patients beginning on Day 1 through Week 52, and up to Week 104.

Experimental: BYM338/bimagrumab Low Dose

60 patients who meet all inclusion criteria and none of the exclusion criteria will be treated with the BYM338 Low Dose administered via intravenous infusion from Day 1 to Week 52, and up to Week 104.

Drug: BYM338/bimagrumab

BYM338 will be administered via intravenous infusion to randomized patients beginning on Day 1 through Week 52, and up to Week 104.

Placebo Comparator: Placebo

60 patients who meet all inclusion criteria and none of the exclusion criteria will be receive matching placebo administered via intravenous infusion from Day 1 to Week 52, and up to Week 104.

Drug: Placebo

Matching placebo will be administered via intravenous infusion to 60 randomized patients beginning on Day 1 through Week 52, and up to Week 104.

Eligibility

Ages Eligible for Study:

36 Years to 85 Years

Genders Eligible for Study:

Both

Accepts Healthy Volunteers:

No

Criteria

Inclusion Criteria:

Diagnosed with sporadic inclusion body myositis;

Must be able to walk (assistive aids allowed, including intermittent use of wheelchair);

Exclusion Criteria:

Must not have other conditions that significantly limit ability to move around;

Must not be using corticosteroids. Must not have used systemic corticosteroid (at daily dose >=10mg prednisone) for the past 3 months;

Must meet cardiovascular requirements;

Must not be pregnant or nursing;

Must not have a chronic active infection (e.g., HIV, hepatitis B or C, tuberculosis, etc); Other protocol-defined inclusion/exclusion criteria may apply

Contacts and Locations

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study.
To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below.
For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01925209